Germans are losing patience with Greece after the protracted debate over its debt crisis and more than half want it to leave the euro zone, according to an opinion poll by ZDF television published on Friday.

The Politbarometer poll showed a sharp swing against Athens in recent months - a similar ZDF survey in January found just a third of Germans wanted Greece to leave and 55 percent to stay.

Friday's poll found 51 percent of Germans wanted Greece to leave the single currency, and 70 percent were opposed to any further concessions towards Athens by the European Union.

Chancellor Angela Merkel urged Greece and its creditors on Friday to keep pushing for a cash-for-reforms deal after negotiations hit stalemate, while Athens refused to back down and accused the IMF of using pressure tactics.

Separately, a leader of the radical Left party in Germany that has long defended efforts to rescue Greece, said an orderly euro zone exit would make sense provided the European Central Bank (ECB) took steps to ensure that the new Greek currency "doesn't collapse into the ground."

Sahra Wagenknecht added that one conceivable plan would be to re-introduce Greece's old currency, the drachma, but make sure the ECB continues to support it "so that it isn't devalued more than about 30 percent."